JPH10199018A - Optical pickup device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical pickup device capable of reproducing two kinds of disks with different densities with a simple constitution, by operating integrally an objective lens part with a beam splitter part. SOLUTION: A laser beam emitted from a laser diode 110 is reflected by a third coating surface 146 of a third beam splitter 145. This reflection beam is reflected partially by a second coating surface 144 of a second beam splitter 143, and goes toward a second objective lens 122, and another part is made incident on a first coating surface 142 at an angle of 45 deg.. When an optical disk 190 to be reproduced is a CD, the beam through a second objective lens 122 for CD is focused on the CD. When the optical disk 190 to be reproduced is a DVD, the beam through a first lens 121 for DVD is focused on the DVD precisely.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical pickup device, and more particularly, to an optical pickup device capable of reproducing two types of discs having different densities by forming a double beam focus having different sizes.

[0002]

2. Description of the Related Art Recently, a data reproducing / recording system using an optical disk such as a laser disk or a compact disk has been developed. Such an optical disc has various kinds of information. For example, there are digital audio discs for playing music and digital video discs for playing video. On these discs, information of an appropriate recording density is recorded according to the use. That is, a digital audio disc for reproducing music is recorded at a lower density, and a digital video disc for reproducing video is recorded at a higher density (for example, about four times the density). Such a disc can record and reproduce information stored therein by an optical pickup device, but different types of discs having different densities as described above must be reproduced by different optical pickup devices.

The construction and operation of a general optical pickup device are disclosed in US Pat. No. 4,767,921 or 4,868,377. Hereinafter, a conventional optical pickup device will be described in detail with reference to FIG.
FIG. 1 is a schematic view of a conventional general optical pickup device. In FIG. 1, reference numeral 11 denotes a laser diode as a light source for generating a laser beam. The laser beam emitted from the laser diode 11 is diffracted while passing through the diffraction grating 12. The diffracted beam goes to the beam splitter 13.

Here, the beam splitter 13
Two right-angle prisms are installed so that their inclined surfaces (45 °) face each other, and a coating layer 13a is formed on the inclined surfaces of the prisms, thereby ensuring the straightness of the incident beam while ensuring the straightness of the incident beam. Will be transmitted and the other will be reflected at an angle of 90 ° to the incident beam.

[0005] The diffracted beam is reflected by the beam splitter 13 toward the optical disk 15. The beam reflected from the beam splitter 13 passes through an objective lens 14 installed in front of a recording medium such as an optical disk 15 while recording on the recording surface 1 of the optical disk.
The focus is on 5a. This photodetector 16
The position accuracy of the pickup device with respect to the disk, that is, the focusing error and the tracking error are detected from the image of the received beam, and the focusing and tracking can be controlled based on the detected accuracy. Further, information is reproduced based on the amount of reflected light determined by the pits on the recording surface of the optical disk 15.

However, in the case of a digital video disk whose recording capacity is four times as large as that of a digital audio disk, the width of the pits on the disk is reduced to half. Therefore, the digital video disk must be configured so that the size of the focused spot is reduced to half of that of the digital audio disk, and the digital video disk and the digital audio disk are reproduced by the conventional optical pickup device. Must use different optical pickup devices. That is, in order to accurately reproduce the data recorded on the digital audio disk and the digital video disk, a beam for a digital audio disk having a beam spot diameter of about 1.6 μm is focused on the digital audio disk. Using a pickup device, the diameter of the focused beam spot on the digital video disc is about 0.8
An optical pickup device for μm digital video discs must be used.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide an optical pickup device capable of reproducing two types of discs having different densities with a simple structure by integrally operating an objective lens unit and a beam splitter unit. Is to provide. Another object of the present invention is to provide an optical pickup device capable of performing recording and reproduction on two types of disks having different densities by a simple configuration by integrally operating an objective lens unit and a beam splitter unit. It is in.

[0008]

According to the present invention, there is provided a laser light source for irradiating a laser beam to reproduce information on optical disks having different densities; The first and second objective lenses are disposed on the optical path of the beam and focused on optical disks of different densities, respectively, for focusing the beams emitted from the laser light source. An objective lens unit disposed side by side; including first and second beam splitters disposed below the objective lens unit and aligned below the first and second objective lenses, respectively; A beam splitter unit driven integrally, and a laser beam incident from the outside is provided inside the first and second beam splitters on the first and second beam splitters. First and second coating surfaces for reflecting toward the second objective lens, respectively, wherein the first and second coating surfaces are arranged in parallel with each other, and the first and second coating surfaces are partially reflected and partially transmitted; A beam splitter section for reflecting a part of the beam incident on the second coating surface as a surface toward the second objective lens and transmitting another part toward the first coating surface; A third beam splitter integrally formed on a side surface of the second beam splitter so as to be driven integrally with the beam splitter unit, wherein a beam emitted from the laser light source is supplied to the inside of the third beam splitter; A third beam splitter having a third coating surface for reflecting toward a second coating surface of the splitter; A wire-type actuator for freely moving the objective lens unit, the beam splitter unit, and the third beam splitter freely forward, backward, left, and right by a wire for information reproduction, tracking, and focusing control of an optical disc having a low density; After being reflected from the optical disk by a photodetector fixedly formed at a predetermined position below the splitter,
An optical detector for receiving a beam transmitted through the first or second beam splitter via the first or second objective lens.

The first, second and third beam splitters are cubic prisms of the same size, and the first, second and third coating surfaces are formed on diagonal surfaces thereof, and the diagonal surface is an objective lens. Is formed at an angle of 45 ° to the optical axis. The laser light source and the photodetector,
When the information on the optical disk is reproduced, an optical disk having a predetermined density, an objective lens corresponding to the optical disk, and a beam splitter fixed below the optical disk are provided by being arranged side by side at the same interval as the interval between the beam splitters. And the photodetectors are aligned.

[0010] The third coating surface of the third beam splitter is formed as a total reflection surface to minimize beam loss. In order to achieve the above object, the present invention provides a laser light source for irradiating first and second polarized laser beams at a constant ratio to reproduce information on an optical disk having different densities; The first and second objective lenses are arranged on an optical path of the generated beam, and are respectively provided on the optical discs having different densities for focusing the beams emitted from the laser light source. An objective lens unit disposed below the objective lens unit and including first and second beam splitters arranged below the first and second objective lenses, respectively; A beam splitter unit driven integrally with the first and second beam splitters. Laser beams incident from outside are first and second beam splitters inside the first and second beam splitters. First and second polarization planes for reflecting or transmitting toward the object lens, wherein the first and second polarization planes are arranged in parallel with each other, and are transmitted between the first and second beam splitters; By forming a polarization conversion surface for converting the polarization of the beam to be emitted, of the beams incident on the second polarization surface,
The laser beam of the first polarization is reflected and directed to the second objective lens, and the laser beam of the second polarization is transmitted and transmitted through the polarization conversion surface to be polarized and converted into the first polarized light. A beam splitter unit for reflecting the beam by the first polarization plane toward the first objective lens; and a polarization conversion plate installed between the objective lens unit and the beam splitter unit. A polarization conversion plate for converting the first polarization beam reflected from the first or second polarization plane to the second polarization by the polarization conversion plate when returning to the beam splitter via the optical disc; and the beam splitter. A third beam splitter integrally formed on a side surface of the second beam splitter so as to be integrally driven with the third beam splitter; A third beam splitter having a first coating surface for reflecting a beam emitted from the laser light source toward a second polarization plane of the second beam splitter; information reproduction of optical discs having different densities; A wire-type actuator for moving the objective lens unit, beam splitter unit, and third beam splitter unit together freely by wire in the forward, backward, left and right directions for tracking and focusing control; and at a predetermined position below the beam splitter unit. After it is reflected from the optical disk by the fixed photo detector,
An optical detector for receiving a beam transmitted through the first or second beam splitter via the first or second objective lens.

The polarization conversion surface provided between the first beam splitter and the second beam splitter is a λ / 2 polarization surface. The polarization conversion plate provided between the objective lens unit and the beam splitter unit is a λ / 4 polarization plate.
According to another aspect of the present invention, there is provided a first and second laser light sources for irradiating laser beams having different wavelengths for recording or reproducing information on an optical disc having different densities; The first and second objective lenses are disposed on an optical path of a beam emitted from the laser light source, and are installed on the optical discs having different densities to focus the beams emitted from the laser light source, respectively. An objective lens unit disposed in parallel and integrally with the first lens unit; a first lens unit disposed below the objective lens unit and aligned below the first and second objective lenses, respectively.
And a second beam splitter, which is driven integrally with the objective lens unit. A laser beam incident from the outside is applied to the inside of the first and second beam splitters by the first and second objectives on the upper side. A first and a second coating surface for reflecting light toward the lens, wherein the first and the second coating surfaces are arranged in parallel with each other, and the first and the second coating surfaces are partially reflected and partially transmitted surfaces. A beam splitter unit for reflecting a part of the beam incident on the second coating surface toward the second objective lens and transmitting another part of the beam toward the first coating surface; Third and fourth beam splitters formed integrally on the side of the second beam splitter so as to be driven integrally with the splitter section. A third and fourth coating surface for reflecting a laser beam incident from the outside toward the second coating surface on the side, wherein the third and fourth beam splitters each have a reflection portion formed therein. The third and fourth coating surfaces are arranged in parallel with each other, and the third coating surface is a partial reflection / partial transmission surface, and a beam emitted from the first laser light source is reflected by the third coating surface and is reflected by the second beam splitter. The beam emitted from the second laser light source toward the second coating surface is reflected by the fourth coating surface, partially transmitted through the third coating surface, and directed toward the second coating surface of the second beam splitter. For information reproduction, tracking and focusing control of optical discs of different densities A wire type actuator for freely moving the objective lens unit, the beam splitter unit and the reflecting unit integrally back and forth and right and left by a wire; and an optical disk fixedly formed at a predetermined position below the beam splitter. And a photodetector for receiving a beam that has passed through the first or second beam splitter through the first or second objective lens after being reflected from the optical pickup device.

According to another aspect of the present invention, there is provided a first and second laser light sources for irradiating laser beams having different wavelengths for recording or reproducing information on an optical disk having different densities. A laser light source for irradiating the first and second polarized laser beams at a fixed ratio; and a laser light source disposed on an optical path of a beam generated from the laser light source;
An objective lens unit provided for focusing the beams emitted from the laser light sources on optical disks having different densities, and an objective lens unit in which first and second objective lenses are integrally arranged in parallel with the disk surface; A beam splitter unit installed below the objective lens unit, the beam splitter unit including first and second beam splitters respectively aligned below the first and second objective lenses, and driven integrally with the objective lens unit; The first and second beam splitters have first and second polarization planes for reflecting or transmitting a laser beam incident from the outside toward the first and second objective lenses, respectively. The second polarization plane is disposed parallel to each other, and forms a polarization conversion plane between the first and second beam splitters for converting the polarization of the transmitted beam. Thereby, of the beams incident on the second polarization plane, the first polarization laser beam is reflected and directed to the second objective lens, and the second polarization laser beam is transmitted and transmitted through the polarization conversion plane. A beam splitter for converting the polarized first polarized light into a first polarized light, and reflecting the converted first polarized light toward the first objective lens; and the objective lens unit and the beam splitter unit. When the first polarized beam reflected from the first or second polarization plane of the beam splitter returns to the beam splitter via the optical disk, the polarization converter is disposed between the first and second polarization converters. 2
A polarization conversion plate for converting the polarized light into polarized light; and reflection comprising a third and a fourth beam splitter integrally formed on a side surface of the second beam splitter so as to be driven integrally with the beam splitter. The third and fourth beam splitters have third and fourth coating surfaces inside the third and fourth beam splitters for reflecting a laser beam incident from the outside toward a second polarization plane on the side. The coating surfaces are arranged in parallel with each other, and the third coating surface is a partially reflecting / partially transmitting surface. A beam emitted from a first laser light source is reflected by the third coating surface and a second polarization surface of the second beam splitter. , And the beam emitted from the second laser light source
A reflector for reflecting the light by the coating surface and partially transmitting the third coating surface to the second polarization surface of the second beam splitter; for controlling information reproduction, tracking, and focusing of optical discs having different densities; A wire-type actuator for freely moving the objective lens unit, the beam splitter unit, and the reflecting unit forward, backward, left, and right by a wire; and a photodetector fixedly formed at a predetermined position below the beam splitter unit. After the reflection from the optical disc, the first
Or a photodetector for receiving a beam transmitted through the first or second beam splitter via a second objective lens.

As described above, according to the optical pickup device of the present invention, two types of discs having different densities can be reproduced by using the objective lenses having different types of objective lenses. Since the lens unit and the beam splitter unit are integrally formed vertically and operated integrally by the objective lens actuator, the number of essential components of the optical pickup device is reduced, and the operation of the objective lens unit and the beam splitter unit is simplified. Thus, the error occurrence rate during the reproduction operation of the optical disk is reduced.

[0014] Further, the beam splitter section can be easily replaced with a fourth.
Only a configuration in which a beam splitter is mounted and a second laser light source that irradiates a laser beam of a different wavelength toward the fourth beam splitter is further provided, a CDR (Compact Diode) that requires a laser beam of a different wavelength.
The information can be recorded on, for example, a sc Recordable) or the information can be reproduced.

Therefore, even in the case of a compact disk and a digital video disk having different recording capacities, the use of the optical pickup device of the present invention not only enables reproduction of both disks but also allows the laser beam of another wavelength to be emitted. Even in the case of a required CDR or the like, recording and reproduction with respect to the disc can be sufficiently performed only by adding a simple constituent element at the time of manufacturing the optical pickup device.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an optical pickup device according to the present invention will be described in detail with reference to the accompanying drawings. Embodiment 1 FIG. 2 is a schematic diagram showing a beam path at the time of reproducing information on an optical disk using a second objective lens in an optical pickup device according to Embodiment 1 of the present invention, and FIG. 3 is according to Embodiment 1 of the present invention. FIG. 3 is a schematic diagram showing a beam path when reproducing information from an optical disk using a first objective lens in the optical pickup device.

As shown in FIGS. 2 and 3, in this embodiment, as a light source for generating a laser beam, a CD (compact disk) on which information of different densities are recorded and a DV
D (Digital Video Disc) that can play both 65
A laser diode 110 for generating a laser beam having a wavelength of 0 nm is provided. The above laser diode 11
The objective lens unit 120 is installed above the zero. The objective lens unit 120 has a first objective lens 121 and a second objective lens 122 arranged in parallel to the optical disk surface. The first objective lens 121 and the second objective lens 122 are used to focus beams emitted from the laser diode 110 onto DVDs and CDs having different densities, respectively. A. = 0.6 for DVD objective lens and N.I. A. = 0.4 CD objective lens is used.

A beam splitter section 140 is fixedly mounted on the lower surface of the objective lens section 120.
The beam splitter 140 includes a first beam splitter 141 and a second beam splitter 143,
The first beam splitter 141 and the second beam splitter 143 are arranged below the first objective lens 121 and the second objective lens 122, respectively. The first and second beam splitters 141 and 143 are cubic prisms of the same size. The first coating surface 142 and the second coating surface 144 in the first beam splitter 141 and the second beam splitter 143 are formed to be parallel to a diagonal plane that forms an angle of 45 ° with the optical axis of the objective lens. Therefore, a laser beam is incident from outside the beam splitter section 140 and the first objective lens 1 on the upper side
The light is reflected toward the first and second objective lenses 122, respectively. The first coating surface 142 and the second coating surface 144 are partial reflection / partial transmission surfaces.

A third beam splitter 145 is integrally formed on a side surface of the second beam splitter 143. The third beam splitter 145 is a cubic prism having the same size as the first beam splitter 141 and the second beam splitter 143. The third coating surface 146 in the third beam splitter 145 is disposed on a diagonal surface that forms an angle of 45 ° with the optical axis of the objective lens.
It is formed parallel to the coating surface 142 and the second coating surface 144. The third beam splitter 145
The third coating surface 146 is formed as a total reflection surface to minimize beam loss, but may be a partially reflection surface.

The wire type actuator 150 includes a wire 152 and a driving unit 151. As described above, the objective lens unit 120, the beam splitter unit 140, and the third
The beam splitter 145 is integrally formed, and predetermined portions on both side surfaces thereof are connected to the driving unit 151 by wires 152, so that the beam splitter 145 can be freely moved back and forth and right and left for information reproduction, tracking, and focusing control of the optical disc. is there.

A photodetector 160 is fixedly formed at a predetermined position below the beam splitter section 140.
After being reflected from the optical disk 190, the photodetector 160 transmits a beam transmitted through the first beam splitter 141 via the first objective lens 121 or a second beam splitter 143 via the second objective lens 122. It is installed to receive the transmitted beam.

The laser diode 110 and the photodetector 160 are arranged side by side at the same interval as the width of the cubic-shaped beam splitters 141, 143, and 145, so that an optical disk having a predetermined density can be used for reproducing information on the optical disk. The objective lens corresponding to the optical disc, the beam splitter fixed below the objective lens, and the photodetector are aligned in a straight line.

Hereinafter, the operation according to the above-described embodiment will be described. A laser beam is emitted from the laser diode 110 toward the third beam splitter 145.
The beam is incident on the third coating surface 146 of the third beam splitter 145 at an incident angle of 45 °. This beam is reflected by the third coating surface 146 at an angle of 90 ° to the angle of incidence.

The reflected beam is incident on the second coating surface 144 of the second beam splitter 143 at an incident angle of 45 °. A part of this beam is reflected by the second coating surface 144 at an angle of 90 ° with respect to the incident angle and travels toward the second objective lens 122 (CD objective lens), and the other part transmits and passes through the second objective lens 122. The light is incident on one coating surface 142 at an incident angle of 45 °.

If the optical disk to be reproduced is a CD
In this case, the beam passing through the first objective lens 121 for DVD is discarded without being accurately focused on the optical disc, and the beam passing through the second objective lens 122 for CD is accurately focused on the CD. You. The objective lens unit 120, the beam splitter unit 140, and the third beam splitter 145 formed integrally are configured such that predetermined portions on both side surfaces thereof are driven by wires 152 by wires 152.
It is connected to. Therefore, information reproduction, tracking, and focusing control of the CD can be performed by aligning the recording pits in the CD, the second objective lens 122 for the CD, the second beam splitter 143, and the photodetector 160 in a straight line. As described above, the objective lens unit 120, the beam splitter unit 140, and the third beam splitter 145 formed integrally are connected to the actuator 1
It is freely moved back and forth and right and left by driving 50.

Thus, the second objective lens 122 for CD
The beam focused on the CD via the optical disc is reflected, and enters the second beam splitter 143 via the second objective lens 122 for the CD. The incident beam partially passes through the second coating surface 144 of the second beam splitter 143, is then focused by the focusing lens 161 and received on the photodetector 160,
The reproduction, tracking, and focusing of the information recorded on D are controlled.

If the optical disk to be reproduced is a DV
If it is D, the beam passing through the second objective lens 122 for CD is discarded without being accurately focused on the optical disc, and the beam passing through the first objective lens 121 for DVD is accurately focused on the DVD. Is done.
By aligning the recording pits in the DVD, the first objective lens 121 for the DVD, the first beam splitter 141, and the photodetector 160 on a straight line, information reproduction, tracking, and focusing control of the DVD can be integrally performed. The formed objective lens unit 120, beam splitter unit 140, and third beam splitter 1
45 is freely moved back and forth and left and right by driving the actuator 150.

Thus, the first objective lens 12 for DVD
The beam focused on the DVD via 1 is reflected and enters the first beam splitter 141 via the first objective lens 121 for DVD. This incident beam partially transmits through the first coating surface 142 of the first beam splitter 141, and then passes through the focusing lens 161.
The light is focused on the photodetector 160 and is received on the photodetector 160, thereby performing operations of reproducing, tracking, and focusing information recorded on the DVD.

Embodiment 2 FIG. 4 is a schematic view of an optical pickup device according to Embodiment 2 of the present invention. In this embodiment, as shown in FIG. 3, a laser diode 2 for generating a laser beam having a wavelength of 650 nm capable of reproducing both CDs and DVDs on which information is recorded at different densities as a light source for generating a laser beam.
10 is installed. The laser diode 210 is installed so as to irradiate P-polarized and S-polarized laser beams at a ratio of 1: 1.

An objective lens section 120 is provided above the laser diode 210. This objective lens section 12
0 is the same as in the first embodiment. The objective lens section 12
The polarization conversion plate 230 is formed on the lower surface of the zero. The polarization conversion plate 230 is a λ / 4 plate. The beam splitter 240 is fixed to the lower surface of the polarization conversion plate 230. The beam splitter section 24
Reference numeral 0 denotes a first beam splitter 241 and a second beam splitter 243, and the first beam splitter 24
The first and second beam splitters 243 are arranged below the first objective lens 121 and the second objective lens 122, respectively. The first beam splitter 241 and the second beam splitter 243 are cubic prisms of the same size. First polarization plane 242 in first beam splitter 241 and second beam splitter 243
And the second plane of polarization 244 is 45 ° from the optical axis of the objective lens.
Are formed parallel to each other on a diagonal plane forming an angle. The first polarization plane 242 and the second polarization plane 244 are polarization planes that totally reflect the P-polarized light beam and completely transmit the S-polarized light beam.

The first beam splitter 241 and the second beam splitter 241
Between the beam splitter 243 and a beam splitter 243, a polarization conversion surface 231 for converting the polarization of a beam transmitted through the beam splitter is formed. The polarization conversion surface 231 has a wavelength of λ /
Two plates. A third beam splitter 145 is integrally formed on a side surface of the second beam splitter 243. The third beam splitter 145 is the same as in the first embodiment.

The objective lens section 120, the polarization conversion plate 230,
The beam splitter unit 240 and the third beam splitter 145 are integrally formed, and predetermined portions on both side surfaces thereof are connected to the driving unit 151 by wires 152, so that information reproduction, tracking, and focusing control of the optical disc are performed by the wire type actuator 150. It can move freely back and forth and left and right as a single unit.

As in the first embodiment, the photodetector 160 is located at a predetermined position below the beam splitter section 240.
Is fixedly formed. The photodetector 160 transmits a beam that has been reflected from the optical disc 190 and has passed through the first beam splitter 241 via the first objective lens 121 or a second beam splitter 243 via the second objective lens 122. It is installed to receive the transmitted beam.

By arranging the laser diode 210 and the photodetector 160 side by side at the same interval as the width of the cubic-shaped beam splitters 241, 243, and 145, an optical disk having a predetermined density when reproducing information on the optical disk can be used. The objective lens corresponding to the optical disc, the beam splitter fixed below the objective lens, and the photodetector are aligned in a straight line.

Hereinafter, the operation according to the above-described embodiment will be described. A laser beam having P-polarized light and S-polarized light at a ratio of 1: 1 is emitted from the laser diode 210 toward the third beam splitter 145. The beam is applied to the third coating surface 1 of the third beam splitter 145.
It is incident on 46 at an incident angle of 45 °. This beam is reflected by the third coating surface 146 at an angle of 90 ° to the angle of incidence.

The reflected beam is incident on the second polarization plane 244 of the second beam splitter 243 at an incident angle of 45 °. Among these beams, the P-polarized beam is reflected by the second polarization plane 244 at an angle of 90 ° with respect to the incident angle, travels toward the second objective lens 122 (CD objective lens), and the S-polarized beam is transmitted. To the first polarization plane 242
Incident angle of °.

If the optical disk to be reproduced is a CD
In this case, the beam passing through the first objective lens 121 for DVD is discarded without being accurately focused on the optical disc, and the beam passing through the second objective lens 122 for CD is accurately focused on the CD. You. In this way, the beam focused on the CD via the second objective lens 122 for the CD is reflected and reflected by the CD.
To the second beam splitter 243 via the second objective lens 122. This beam is transmitted to the second objective lens 1
Since the light reciprocates and passes through the polarization conversion plate 230, which is a λ / 4 plate, between the second beam splitter 243 and the second beam splitter 243, the light is converted into S-polarized light. The S-polarized beam partially transmits through the second polarization plane 244 of the second beam splitter 243 and is then focused by the focusing lens 161 and received on the photodetector 160, thereby reproducing information recorded on the CD. The control operation of tracking and focusing is performed.

For controlling tracking and focusing, the objective lens section 120, the beam splitter section 240 and the third beam splitter 14 are integrally formed.
5 is freely moved back and forth and right and left by driving the actuator 150. If the optical disk to be reproduced is a DVD, the second objective lens 122 for CD
Is discarded without being accurately focused on the optical disk, and the first objective lens 121 for DVD
Is focused on the DVD accurately.

Thus, the first objective lens 12 for DVD
The beam focused on the DVD via 1 is reflected and enters the first beam splitter 241 via the first objective lens 121 for DVD. The incident beam is applied to the first polarization plane 2 of the first beam splitter 241.
42 is partially transmitted, and then focused by the focusing lens 161 and received on the photodetector 160,
The reproduction, tracking, and focusing of the information recorded on the DVD are controlled.

An objective lens unit 1 integrally formed for controlling reproduction, tracking and focusing of information.
20, the beam splitter unit 240 and the third beam splitter 145 are freely moved back and forth and right and left by driving the actuator 150. Embodiment 3 FIG. 5 is a schematic diagram showing a beam path when recording and reproducing information on an optical disk by a second laser light source in an optical pickup device according to Embodiment 3 of the present invention.

In this embodiment, as shown in FIG. 5, as a light source for generating a laser beam, a laser beam having a wavelength of 650 nm capable of reproducing both a CD and a DVD on which information of different densities is recorded is generated. 1 laser diode 31
0 and compact disc (CD
A second laser diode 320 for generating a laser beam having a wavelength of 780 nm for recording information on a disc (R: Compact Disc Recordable) or reproducing the information is arranged side by side in parallel with the optical disc surface.

The first laser diode 310 and the second
The objective lens unit 120 is provided above the laser diode 320.
Is installed. This objective lens unit 120 is the same as in the first embodiment. A beam splitter section 140 is fixed to the lower surface of the objective lens section 120. The beam splitter section 140 is also the same as in the first embodiment.

A reflection section 340 is formed on a side surface of the second beam splitter 143 of the beam splitter section 140. The reflection unit 340 includes a third beam splitter 345 and a fourth beam splitter 3 which are integrally formed.
Consists of 47. The third beam splitter 345 and the fourth beam splitter 347 are cubic prisms having the same size as the first beam splitter 141 and the second beam splitter 143. Third coating surface 346 and fourth coating surface 3 in third beam splitter 345 and fourth beam splitter 347
48 denotes the first lens which forms an angle of 45 ° with the optical axis of the objective lens.
It is formed parallel to the coating surface 142 and the second coating surface 144. The third beam splitter 345
The third coating surface 346 and the fourth coating surface 348 of the fourth beam splitter 347 are partially reflecting surfaces. As the fourth coating surface 348, a total reflection surface is selected to minimize beam loss.

The wire type actuator 150 includes a wire 152 and a driving unit 151. As described above, the objective lens unit 120, the beam splitter unit 140, and the reflection unit 340 are integrally formed, and predetermined portions on both side surfaces thereof are connected to the driving unit 151 by the wires 152,
For information reproduction, tracking, and focusing control of the optical disc, the optical disc is freely moved back and forth, right and left in an integrated manner.

A photodetector 160 is fixedly formed at a predetermined position below the beam splitter section 140.
The photodetector 160 transmits a beam that has been reflected from the optical disc 390 and has passed through the first beam splitter 141 via the first objective lens 121, or a second beam splitter 143 via the second objective lens 122. It is installed to receive the transmitted beam.

The first laser diode 310, the second laser diode 320, and the photodetector 160
Is the beam splitter 14 having the cubic shape.
1, 143, 345, 347 are arranged side by side at the same interval as the width of the optical disk, so that when reproducing information on the optical disk, an optical disk having a predetermined density, an objective lens corresponding to the optical disk, and a beam fixed below the optical disk. The splitter and photodetector will be aligned.

Hereinafter, the operation according to the above-described embodiment will be described. The first laser diode 310 for irradiating a 650 nm beam is the laser diode 11 of the first embodiment.
It is similar to the case of 0. When a laser beam is emitted from the second laser diode 320 that emits a 780 nm beam, this beam is emitted by the fourth beam splitter 347.
At an incident angle of 45 °. This beam is reflected by the fourth coating surface 148 at an angle of 90 ° with respect to the angle of incidence.

The reflected beam semi-transmits through the third coating surface 346 of the third beam splitter 345,
Second coating surface 1 of second beam splitter 143
The light 44 is incident at an incident angle of 45 °. A part of this beam is reflected by the second coating surface 144 at an angle of 90 ° with respect to the incident angle, and the second objective lens 122 (C
The other part is transmitted and enters the first coating surface 142 at an angle of 45 °.

If the optical disk to be recorded is a CD
If R, the beam passing through the first objective lens 121 for DVD is discarded without being accurately focused on the optical disk, and the beam passing through the second objective lens 122 for CD is accurately focused on the CDR. Is done.
Thus, information can be recorded on the CDR. CD
The beam focused on the CDR via the second objective lens 122 for CD is reflected and passed through the second objective lens 122 for CD to the second beam splitter 143.
Incident on. The incident beam partially transmits through the second coating surface 144 of the second beam splitter 143, and is then focused by the focusing lens 161 and received on the photodetector 160, thereby performing a tracking and focusing control operation.

In order to control tracking and focusing, the objective lens unit 120, the beam splitter unit 140, and the reflecting unit 340, which are integrally formed, are freely moved back and forth and right and left by driving the actuator 150. Embodiment 4 FIG. 6 is a schematic view of an optical pickup device according to Embodiment 4 of the present invention.

In this embodiment, as shown in FIG. 6, as a light source for generating a laser beam, a laser beam having a wavelength of 650 nm capable of reproducing both a CD and a DVD on which information of different densities is recorded is generated. 1 laser diode 31
0 and compact disc (CD
R) 780n for recording information and reproducing information
A second laser diode 320 for generating a laser beam having a wavelength of m is arranged side by side in parallel with the optical disk surface.

The first laser diode 310 and the second
The objective lens unit 120 is provided above the laser diode 320.
Is installed. This objective lens unit 120 is the same as in the first embodiment. A polarization conversion plate 230 is formed on the lower surface of the objective lens unit 120. The polarization conversion plate 230 is λ / 4
It is a plate.

The beam splitter 240 is fixed to the lower surface of the polarization conversion plate 230. The beam splitter unit 240 includes a first beam splitter 241 and a second beam splitter 243,
The first beam splitter 241 and the second beam splitter 243 are aligned below the first objective lens 121 and the second objective lens 122, respectively. The first beam splitter 241 and the second beam splitter 243 are cubic prisms of the same size. First and second polarization planes 242 and 244 in the first and second beam splitters 241 and 243, respectively.
Are formed parallel to each other on a diagonal plane which forms an angle of 45 ° with the optical axis of the objective lens. The first polarization plane 242 and the second polarization plane 244 are polarization planes that totally reflect the P-polarized beam and completely transmit the S-polarized beam.

The first beam splitter 241 and the second beam splitter 241
Between the beam splitter 243 and a beam splitter 243, a polarization conversion surface 231 for converting the polarization of a beam transmitted through the beam splitter is formed. The polarization conversion surface 231 has a wavelength of λ /
Two plates. The second of the beam splitter section 240
A reflecting portion 340 is integrally formed on a side surface of the beam splitter 243. As in the third embodiment, the reflection unit 340 is used.
Is a third beam splitter 34 formed side by side
5 and a fourth beam splitter 347. The third beam splitter 345 and the fourth beam splitter 347 are cubic prisms having the same size as the first beam splitter 241 and the second beam splitter 243. The third coating surface 346 and the fourth coating surface 348 in the third beam splitter 345 and the fourth beam splitter 347 form the first polarization surface 242 and the second polarization surface 245 which are at 45 ° to the optical axis of the objective lens.
It is formed parallel to the polarization plane 244. The third coating surface 346 and the fourth coating surface 348 of the third beam splitter 345 and the fourth beam splitter 347.
Is a partially reflecting surface. As the fourth coating surface 348, a total reflection surface is selected to minimize beam loss.

The wire type actuator 150 includes a wire 152 and a driving unit 151. As described above, the objective lens unit 120, the beam splitter unit 240, and the reflecting unit 340 are integrally formed, and predetermined portions on both side surfaces thereof are connected to the driving unit 151 by the wires 152.
For information reproduction, tracking, and focusing control of the optical disc, the optical disc is integrally and freely moved back and forth and left and right.

A photodetector 160 is fixedly formed at a predetermined position below the beam splitter section 240.
The photodetector 160 transmits a beam that has been reflected from the optical disc 390 and has passed through the first beam splitter 241 via the first objective lens 121 or transmitted through the second beam splitter 243 via the second objective lens 122. It is installed to receive the beam.

The first laser diode 310, the second laser diode 320, and the photodetector 160
Is the cubic beam splitter 24
1, 243, 345, and 347 are arranged side by side at the same interval, so that when reproducing information on the optical disk, an optical disk having a predetermined density, an objective lens corresponding to the optical disk, and a beam fixed below the optical disk. The splitter and photodetector will be aligned.

Hereinafter, the operation according to the above-described embodiment will be described. The first laser diode 310 for irradiating a 650 nm beam is the laser diode 11 of the first embodiment.
It is similar to the case of 0. When a laser beam is emitted from the second laser diode 320 that emits a 780 nm beam, this beam is emitted by the fourth beam splitter 347.
At an incident angle of 45 °. This beam is reflected by the fourth coating surface 348 at an angle of 90 ° to the angle of incidence.

The reflected beam semi-transmits through the third coating surface 346 of the third beam splitter 345,
The second polarization plane 244 of the second beam splitter 243
It is incident at an incident angle of 5 °. Of the beams, the P-polarized beam is 9 degrees with respect to the incident angle by the second polarization plane 244.
The light is reflected at an angle of 0 ° toward the second objective lens 122 (CD objective lens), and the S-polarized beam is transmitted to the first objective lens 122 (the first objective lens 122).
The light enters the polarization plane 242 at an angle of 45 °.

If the optical disk to be recorded is a CD
If R, the beam passing through the first objective lens 121 for DVD is discarded without being accurately focused on the optical disc, and the beam passing through the second objective lens 122 for CD is accurately focused on the CDR. Is done.
Thus, information can be recorded on the CDR. The beam focused on the CDR via the polarization conversion plate 230 and the second objective lens 122 for CD is reflected and reflected by the second objective lens 122 for CD and the polarization conversion plate 23.
Then, the light enters the second beam splitter 243 via 0. The incident beam partially transmits through the second polarization plane 244 of the second beam splitter 243,
The light is converged by 1 and is received on the photodetector 160 to perform a tracking and focusing control operation.

As described above, according to the optical pickup device of the present invention, two types of discs having different densities can be reproduced by using the objective lens section having two types of objective lenses different from each other. Since the objective lens unit and the beam splitter unit are integrally formed vertically and operated integrally by the wire type actuator, the number of essential components of the optical pickup device is reduced, and the operation of the objective lens unit and the beam splitter unit is simplified. Thus, the error occurrence rate during the reproduction operation of the optical disk is reduced.

Further, the beam splitter section is simply provided with a fourth
Only by installing a beam splitter and further installing a second laser light source for irradiating a laser beam of a different wavelength toward the fourth beam splitter, information can be recorded and recorded in a CDR or the like that requires a laser beam of a different wavelength. Can be played. Therefore, in the case of a compact disk and a digital video disk having different recording capacities, the use of the optical pickup device of the present invention not only enables reproduction of both disks but also requires a laser beam of another wavelength. Even in the case of a CDR or the like, recording and reproduction with respect to a corresponding disc can be sufficiently performed only by adding a simple constituent element at the time of manufacturing the optical pickup device.

Although the present invention has been specifically described based on the above embodiments, the present invention is not limited to these embodiments, and can be changed and improved without departing from the gist of the present invention. Of course.

[Brief description of the drawings]

FIG. 1 is a schematic view of a conventional optical pickup device.

FIG. 2 is a schematic diagram showing a beam path when reproducing information from an optical disk using a second objective lens in the optical pickup device according to the first embodiment of the present invention.

FIG. 3 is a schematic diagram showing a path of a beam when reproducing information from an optical disc using a first objective lens in the optical pickup device according to the first embodiment of the present invention.

FIG. 4 is a schematic diagram of an optical pickup device according to a second embodiment of the present invention.

FIG. 5 is a schematic diagram showing a beam path when recording and reproducing information on an optical disk by a second laser light source in the optical pickup device according to Embodiment 3 of the present invention.

FIG. 6 is a schematic diagram showing a path of a beam when recording and reproducing information on an optical disk by a second laser light source in the optical pickup device according to Embodiment 4 of the present invention.

[Explanation of symbols]

 110, 210, laser diode 120 objective lens section 140, 240 beam splitter section 150 wire-type actuator 160 photodetector 190 optical disk 230 polarization conversion plate 310 first laser diode 320 second laser diode 340 reflecting section

Claims (20)

[Claims] 1. A laser light source for irradiating a laser beam to reproduce information on an optical disk having different densities; and a laser light source arranged on an optical path of a beam irradiated from the laser light source and having different densities. An objective lens unit provided for focusing each of the beams emitted from the laser light source, and an objective lens unit in which first and second objective lenses are integrally arranged in parallel with a disk surface; and a lower portion of the objective lens unit A first and a second beam splitters respectively arranged below the first and the second objective lenses, wherein the first and second beam splitters are driven integrally with the objective lens unit. The first and second objective lenses inside the beam splitter reflect an externally incident laser beam toward the first and second objective lenses, respectively. A second coating surface, wherein the first and second coating surfaces are arranged in parallel with each other, and the first and second coating surfaces are partially reflected and partially transmitted surfaces of the beam incident on the second coating surface. A beam splitter section that reflects part of the beam toward the second objective lens and transmits part of the beam toward the first coating surface; and a second part that is driven integrally with the beam splitter part. A third beam splitter integrally formed on a side surface of the beam splitter, the inside of the third beam splitter for reflecting a beam emitted from the laser light source toward a second coating surface of the second beam splitter; A third beam splitter having a third coating surface; information reproduction, tracking and format of optical discs having different densities; A wire-type actuator for freely moving the objective lens unit, the beam splitter unit, and the third beam splitter in a forward, backward, left, and right direction with a wire for controlling the casing; fixedly formed at a predetermined position below the beam splitter; After being reflected from the optical disk by the photodetector
An optical detector for receiving a beam transmitted through the first or second beam splitter via the first or second objective lens. 2. The first, second and third beam splitters are cubic prisms of the same size, the first, second and third coating surfaces are formed on diagonal surfaces thereof, and the diagonal surface is 2. The optical pickup device according to claim 1, wherein the optical pickup device is configured to form an angle of 45 [deg.] With respect to the optical axis of the objective lens. 3. An optical disk having a predetermined density when reproducing information on an optical disk, wherein the laser light source and the photodetector are arranged side by side at the same interval as the interval between the beam splitters. 3. The optical pickup device according to claim 2, wherein the objective lens corresponding to (1), the beam splitter fixed to the lower part thereof, and the photodetector are aligned in a straight line. 4. The optical pickup device according to claim 1, wherein the third coating surface of the third beam splitter is formed as a total reflection surface to minimize beam loss. 5. A laser light source for irradiating laser beams of first and second polarizations at a fixed ratio to reproduce information on an optical disk having different densities; and on a light path of a beam generated from the laser light source. Are arranged for focusing beams irradiated from the laser light source on optical discs having different densities, and an objective in which first and second objective lenses are arranged integrally and in parallel with the disc surface. A lens unit; first and second beam splitters installed below the objective lens unit and aligned below the first and second objective lenses, respectively;
A beam splitter unit driven integrally with the objective lens unit for reflecting or transmitting a laser beam incident from the outside toward the first and second objective lenses inside the first and second beam splitters; A first and a second polarization plane, wherein the first and the second polarization planes are arranged in parallel with each other, and a polarization conversion for converting a polarization of a transmitted beam between the first and the second beam splitters; By forming the surface, of the beam incident on the second polarization plane, the laser beam of the first polarization is reflected and directed to the second objective lens, and the laser beam of the second polarization is transmitted and passes through the polarization conversion surface. A beam splitter for converting the polarized light into the first polarized light while transmitting the light, and converting the converted first polarized light beam toward the first objective lens after being reflected by the first polarization plane; A first polarization beam reflected from the first or second polarization plane of the beam splitter returns to the beam splitter via the optical disc by a polarization conversion plate provided between the objective lens unit and the beam splitter unit. And a third beam splitter integrally formed on a side surface of the second beam splitter so as to be integrally driven with the beam splitter unit so as to be integrated with the beam splitter unit. A third beam splitter having a first coating surface for reflecting a beam emitted from the laser light source toward a second polarization plane of the second beam splitter inside the third beam splitter; The objective lens unit and the beam for the information reproduction, tracking and focusing control of the optical disc A wire-type actuator for freely moving the splitter portion and the third beam splitter integrally and freely back and forth and left and right; and a photodetector fixedly formed at a predetermined position below the beam splitter portion and reflected from the optical disk. After that, the first or second objective lens passes through the first or second objective lens.
An optical detector for receiving a beam transmitted through the second beam splitter. 6. The optical pickup device according to claim 5, wherein a ratio of the first polarized light and the second polarized light of the laser light source is 1: 1. 7. A polarization conversion surface provided between the first beam splitter and the second beam splitter has a wavelength of λ / 2.
The optical pickup device according to claim 5, wherein the optical pickup device is a polarization plane. 8. The optical pickup device according to claim 5, wherein the polarization conversion plate provided between the objective lens unit and the beam splitter unit is a λ / 4 polarization plate. 9. The first, second and third beam splitters are cubic prisms of the same size, the first, second and third coating surfaces are formed on diagonal surfaces thereof, and the diagonal surface is The optical pickup device according to claim 5, wherein the optical pickup device is configured to form an angle of 45 ° with the optical axis of the objective lens. 10. The optical disc having a predetermined density when reproducing information on an optical disc, wherein the laser light source and the photodetector are arranged side by side at the same interval as the interval between the beam splitters. 10. The optical pickup device according to claim 9, wherein the objective lens corresponding to (1), the beam splitter fixed under the objective lens, and the photodetector are aligned in a straight line. 11. The optical pickup device according to claim 5, wherein the third coating surface of the third beam splitter is formed as a total reflection surface to minimize beam loss. 12. A first and a second laser light source for irradiating laser beams of different wavelengths for recording or reproducing information on an optical disk having different densities; and light beams emitted from the laser light sources. The first and second objective lenses are disposed on a path and are respectively installed on optical disks having different densities to focus the beams emitted from the laser light source, and the first and second objective lenses are installed in parallel with the disk surface in an integrated manner. An objective lens unit; first and second beam splitters installed below the objective lens unit and aligned below the first and second objective lenses, respectively, and are driven integrally with the objective lens unit. In the first and second beam splitters, a laser beam incident from the outside is provided inside the first and second beam splitters. First and second coating surfaces respectively reflecting light toward the lens, and the first and second coating surfaces
The coating surfaces are disposed parallel to each other, and the first and second coating surfaces are partially reflected and partially transmitted surfaces, and a part of the beam incident on the second coating surface is reflected and directed toward the second objective lens, A beam splitter portion for transmitting the other portion toward the first coating surface; and being integrally formed on a side surface of the second beam splitter so as to be driven integrally with the beam splitter portion. A third and fourth beam splitter for reflecting a laser beam incident from the outside toward the second coating surface on the side in the third and fourth beam splitters. A coating surface, wherein the third and fourth coating surfaces are arranged parallel to each other, and the third coating surface is partially reflected and
The beam emitted from the first laser light source as a partially transmitting surface is reflected by the third coating surface and travels toward the second coating surface of the second beam splitter.
A reflecting portion for reflecting the beam emitted from the laser light source by the fourth coating surface, partially transmitting the third coating surface, and heading toward the second coating surface of the second beam splitter; A wire-type actuator for freely moving the objective lens unit, beam splitter unit and reflection unit integrally back and forth and left and right by wires for information reproduction, tracking and focusing control of the optical disc; and a predetermined lower part of the beam splitter A photodetector fixedly formed at a position for receiving a beam reflected from the optical disc and transmitted through the first or second beam splitter via the first or second objective lens; And an optical pickup device. 13. The first, second and third beam splitters are cubic prisms of the same size,
13. The method according to claim 12, wherein the first, second, and third coating surfaces are formed on diagonal surfaces thereof, and the diagonal surfaces are configured to form an angle of 45 degrees with the optical axis of the objective lens. Optical pickup device. 14. An optical disk having a predetermined density when reproducing information on an optical disk, wherein the laser light source and the photodetector are arranged side by side at the same interval as the interval between the beam splitters. 13. The optical pickup device according to claim 12, wherein the objective lens corresponding to (1), the beam splitter fixed to the lower part thereof, and the photodetector are aligned in a straight line. 15. The optical pickup device according to claim 12, wherein the fourth coating surface of the fourth beam splitter is formed as a total reflection surface to minimize beam loss. 16. A first and second laser light source for irradiating laser beams having different wavelengths for recording or reproducing information on or from an optical disk having different densities. A laser light source for irradiating at a fixed ratio; disposed on an optical path of a beam generated from the laser light source, and installed for focusing each of the beams irradiated from the laser light source on optical discs having different densities; An objective lens section in which the first and second objective lenses are integrally arranged in parallel with the disk surface;
The first and second lenses are installed below the objective lens unit.
A beam splitter unit, which includes first and second beam splitters arranged below the objective lens, respectively, and is driven integrally with the objective lens unit. The beam splitter unit enters the first and second beam splitters from the outside. First and second polarization planes for reflecting or transmitting the laser beam toward the first and second objective lenses, wherein the first and second polarization planes are arranged in parallel with each other; 2
By forming a polarization conversion surface for converting the polarization of the transmitted beam between the beam splitters, the laser beam of the first polarization among the beams incident on the second polarization surface is reflected and the second objective lens is formed. , The laser beam of the second polarization is transmitted and transmitted through the polarization conversion surface and is polarization-converted to the first polarization, and the converted first polarization beam is reflected by the first polarization surface and is reflected by the first objective lens. A beam splitter section for directing light toward the first lens; and a first polarized light reflected from a first or second polarization plane of the beam splitter section by a polarization conversion plate provided between the objective lens section and the beam splitter section. A polarization conversion plate for causing the polarization conversion plate to perform polarization conversion to the second polarization when the beam returns to the beam splitter via the optical disk; A reflecting portion including third and fourth beam splitters formed integrally on the side surface of the second beam splitter so as to be driven integrally with the splitter portion, and inside the third and fourth beam splitters. A third coating surface for reflecting a laser beam incident from the outside toward a second polarizing surface on a side, wherein the third and fourth coating surfaces are arranged in parallel with each other; Is a partially reflected / partially transmitted surface, the beam emitted from the first laser light source is reflected by the third coating surface and directed to the second polarization surface of the second beam splitter, and the beam emitted from the second laser light source is The light is reflected by the fourth coating surface, partially passes through the third coating surface, and is directed to the second polarization plane of the second beam splitter. And a wire type actuator for freely moving the objective lens unit, beam splitter unit, and reflecting unit integrally with a wire back and forth and left and right for information reproduction, tracking, and focusing control of optical discs having different densities. And a light detector fixedly formed at a predetermined position below the beam splitter unit, reflected from the optical disk, and transmitted through the first or second beam splitter via the first or second objective lens. An optical detector for receiving the light beam. 17. The optical pickup device according to claim 16, wherein a ratio of the first polarized light and the second polarized light of the laser light source is 1: 1. 18. A polarization conversion surface provided between the first beam splitter and the second beam splitter has a wavelength of λ /
17. The optical pickup device according to claim 16, wherein the optical pickup device has two polarization planes. 19. The optical pickup device according to claim 16, wherein the polarization conversion plate provided between the objective lens unit and the beam splitter unit is a λ / 4 polarization plate. 20. The first, second and third beam splitters are cubic prisms of the same size,
17. The method according to claim 16, wherein the first, second, and third coating surfaces are formed on diagonal surfaces thereof, and the diagonal surfaces are configured to form 45 degrees with respect to an optical axis of the objective lens. Optical pickup device.